EXAM 3 STUDY GUIDE

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The evolution of populations due to chance is
A. has more effect in large populations than in small populations.
B. natural selection.
C. gene flow.
D. genetic variation.
E. genetic drift.

E
Genetic drift describes the evolution of a population due to chance.

If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles,
A. the frequency of the green allele will increase.
B. the frequencies of the brown and green alleles will not change.
C. this causes the population to evolve due to genetic drift.
D. this causes the population to evolve due to gene flow.
E. the frequency of the brown allele will increase.

A
If birds are more likely to eat brown beetles than green beetles, then green beetles will survive and reproduce more than brown beetles. This causes the frequency of the green allele to increase.

In a population with brown and green alleles for color, genetic drift
A. always increases the frequency of brown alleles in the population
B. has more effect on the evolution of a small population.
C. occurs when individuals move into or out of a population, changing the allele frequencies in the population.
D. has more effect on the evolution of a large population.
E. causes populations to become better adapted to their environments.

B
Genetic drift affects the evolution of small populations more than it affects the evolution of large populations.

Color is an inherited trait in beetles. If brown beetles move into a population from a nearby island, which of the following statements is correct?
A. This is an example of genetic drift.
B. Gene flow causes the frequency of the brown allele to increase.
C. Natural selection causes the frequency of the brown allele to increase.
D. Gene flow causes the frequency of the green allele to increase.
E. Natural selection causes the frequency of the green allele to increase.

B
Gene flow occurs when individuals move into or out of a population, changing the allele frequencies in the population. In this case, new brown beetles in the population cause the frequency of the brown allele to increase.

Remember that color is an inherited trait in beetles. Which of the following is an example of natural selection?
a. Green beetles migrate out of the population.
b. Green beetles and brown beetles always leave the same number of offspring.
c. A storm kills more green beetles than brown beetles by chance.
d. Green beetles migrate out of the population, and brown beetles migrate into the population.
e. Green beetles leave more offspring than brown beetles because they are better at finding food.

E
Natural selection occurs when organisms with one inherited trait survive and reproduce more than organisms with other traits.

Generation-to-generation change in the allele frequencies in a population is _____.
a. genetic drift
b. natural selection
c. macroevolution
d. mutation
e. microevolution

E
Generation-to-generation change in the allele frequencies in a population is the definition of microevolution.

An allele is:
a. a genotype
b. a particular trait
c. the gene pool of a population
d. a particular version of a gene

D

A population is:
a. all organisms in the ecosystem
b. all organisms in a given area
c. various alleles at all the gene loci
d. members of the same species occupying the same area at the same time

D

How many alleles do you inherit for each genetic trait?
a. 46
b. 2
c. 1
d. it depends on the specific trait

B
Each parent contributes one allele per trait.

Allelic frequencies change in:
a. an individual
b. single cells
c. a population

C

Which of the following events could NOT be caused by a population bottleneck?
a. Increased population size
b. Reduction in genetic variability
c. Loss of alleles
d. Changes in allele frequency

A
By definition, a population bottleneck dramatically reduces the size of a population.

Feathers either play a role, or may have played a role, in _____.
a. gliding
b. extended hops
c. courtship
d. flight
e. all of these

E

____ is rapid, branching speciation under conditions in which there is little competition.
a. Genetic drift
b. Paedomorphosis
c. Gene flow
d. Adaptive radiation
e. Microevolution

E

Mass extinctions create conditions that promote _____.
a. genetic drift
b. microevolution
c. gene flow
d. paedomorphosis
e. adaptive radiation

E
Mass extinctions reduce competition and allow for periods of rapid speciation.

The appearance of an evolutionary novelty often promotes _____.
a. adaptive radiation
b. gene flow
c. mutation
d. paedomorphosis
e. mass extinction

A
The appearance of an evolutionary novelty may allow for the exploitation of previously unexploited niches.

The only process that can add new genes and therefore new variations to a species is _______.
a. natural selection
b. mutation
c. stabilizing selection
d. selective breeding

B
Mutations are changes to the DNA code. If mutations should prove helpful, they can be passed on to the organism's offspring and add a brand new variation to the species.

Two organisms live in the same geographical area, are very similar genetically, and can breed with each other successfully. Which of the following statements is correct?
a. These organisms have undergone speciation.
b. These organisms are members of the same species.
c. These organisms have gone extinct.
d. These organisms are members of different populations.

B
These organisms have met all of the requirements for being members of the same species.

In order for two organisms to belong to the same species, individuals of their species must _______.
a. live in the same geographical area
b. be of the same sex
c. be able to reproduce and have fertile offspring
d. share more than 30% genetic identity with each other

C
It is very important members of the same species be able to successfully breed with each other.

Which type of selection helps to preserve the status quo, genetically speaking?
a. directional selection
b. disruptive selection
c. stabilizing selection
d. status quo selection

C

An excellent example of selective or artificial breeding by humans is _______.
a. the great diversity of man-made fabrics
b. the diversity of dog breeds in the world today
c. the diversity of human species in the world today
d. the extinction of frogs in Monteverde's cloud forest

B
For many years humans have been breeding different dogs to achieve the most desired characteristics (according to human standards).

Which statement below most accurately describes a phylogenetic tree?
a. A phylogenetic tree is a genetically modified tree that can produce asexually without using seeds.
b. A phylogenetic tree is a branching diagram used to illustrate the steps an organism went through during artificial selection.
c. A phylogenetic tree is a branching diagram used to illustrate a scientist's hypothesis about how divergence took place among evolutionary lines.
d. A phylogenetic tree is a diagram that shows how one species develops into another.

C
By design the phylogenetic tree suggests relatedness. As the phylogenetic premise asserts, similarity of anatomy, physiology, and behavior suggests relatedness.

A single, small population that only exists in one place on the planet is considered _____ to that area.
a. foreign
b. pandemic
c. extinct
d. endemic

D

Which of the following populations would be most vulnerable to extinction?
a. a small, endemic population
b. a small population of generalists
c. a medium-sized specialist population
d. a large population of generalists

A
The smaller the population the more likely that it may become extinct. Small populations, by chance could become extinct because of any given environmental pressure. Endemic populations are also at risk because there are no other environments to which they can migrate successfully.

The sixth mass extinction event is likely being caused by _______.
a. meteorites
b. the last ice age
c. disease pandemics
d. human-induced events

D
A mass extinction is under way and is being caused mostly by humans through habitat alteration and/or destruction, transport of invasive species, and overhunting and overharvesting.

Which of the following would explain the extinction of upwards of 90% of species in existence over a short period of time?
a. mass extinction events
b. dispersal events
c. speciation
d. endemic populations

A
This is the only explanation for such a large percentage of species disappearing from the earth.

Extinction is a(n) _____ process; human activity can affect the _____ at which extinction occurs.
a. unnatural, location
b. unnatural, time
c. natural, rate
d. natural, migration level

C
Extinction occurs naturally at a background rate through time, but human activities can dramatically increase the process of extinction.

Which of the following is considered a community?

a. a single population whose individuals are similar enough to each other to be able to breed successfully
b. an ecosystem
c. all of the living and nonliving things on the earth
d. several interacting species living in the same area

D

Which of the following is the broadest (most all-encompassing) level of ecological organization?

a. a population
b. an ecosystem
c. the biosphere
d. an organism

C
The biosphere represents the entire earth and all of its ecosystems with all living and nonliving things interacting together.

A _____ is defined as the living and nonliving elements around an organism.

a. niche
b. generalist
c. habitat
d. specialist

C

Starting with the smallest level of ecological organization and moving towards the highest, the order should go organism, _________.

a. community, population, biosphere, ecosystem
b. ecosystem, population, community, biosphere
c. biosphere, population, ecosystem, community
d. population, community, ecosystem, biosphere

D

An ideal habitat with unlimited resources is associated with

a. Neither exponential growth nor logistic growth.
b. Logistic growth.
c. Both exponential growth and logistic growth.
d. Exponential growth.
e. Population crashes.

D
Populations grow exponentially with unlimited resources.

The maximum population a habitat can support is its

a. Logistic growth.
b. Carrying capacity.
c. Exponential growth.
d. Death rate.
e. Birth rate.

B

Logistic growth involves

a. Population growth continuing forever.
b. Population size decreasing to zero.
c. Population growth reaching carrying capacity and then speeding up.
d. Population growth slowing down as the population approaches carrying capacity.
e. A population crash.

D

In exponential growth

a. Population growth slows as the population gets close to its carrying capacity.
b. Population size stays constant.
c. Population size grows more and more slowly as the population gets bigger.
d. Population size grows faster and faster as the population gets bigger.
e. None of these are correct.

D

Which of the following would NOT cause population size to decrease?

a. Increase in the number of predators
b. Increased birth rate
c. Poor weather, resulting in less food being available
d. A exponentially growing population outgrowing its food supply and crashing
e. Increased death rate

B
An increased birth rate would cause population size to increase.

The innate reproductive capacity of a species is its _____.

a. environmental resistance
b. carrying capacity
c. biotic potential
d. logistic growth

C
If a parasitic worm makes a very large number of eggs, it has a high biotic potential. These animals are called r-strategists. Elephants have a low biotic potential by comparison, and are called K-strategists.

The carrying capacity is _______.

a. the maximum population size that a given environment can sustain
b. the potential number of species that could exist in a given area
c. always the same for a given habitat
d. the greatest number of niches possible in a given area

A
The population should stabilize at the point of carrying capacity when environmental resistance factors into population control.

What describes the number of individuals in a population per unit area?

a. Population dynamics
b. population gravity
c. population extinction
d. population density

D

When looking at the distribution of a population, we might find a uniform distribution when _______.

a. members of a population try to avoid predators
b. not enough of a resource is available to support the population
c. a resource is found in limited, isolated areas within the habitat
d. individuals are competing for an evenly distributed resource such as space

D
Competition for space often results in each member of the population taking up as much space as possible until they bump up against their neighbor who is doing the same thing. This gives a uniform distribution.

Density-dependent factors _______.

a. have a greater impact at higher population densities
b. cause decreases in numbers of species in an ecosystem as a result of temperature extremes
c. are less important for regulating population size than density-independent factors
d. act at the community level

A
In this way, density-dependent factors help to slow or stop populations from growing once they reach the carrying capacity.

Consider a population of fish in the ocean. Which of the following would be a limiting factor for such a population?

a. the pH of soil
b. atmospheric oxygen levels
c. dissolved oxygen levels
d. rainfall

C
Maintaining a normal level of dissolved oxygen in the water surrounding the fish population would be critical for the survival of the population.

Assuming a population grows by a fixed percentage each year, which of the following starting populations would experience the biggest increase in its population from one year to the next?

a. 1,000 individuals
b. 2,000 individuals
c. 150 individuals
d. 10 individuals

B
A fixed percentage of a population makes for small population growth, but a fixed percentage of a larger population makes for larger population growth.

Which of the following would be the most effective action for protecting biodiversity?

a. practice ecotourism
b. practice preservation
c. practice conservation
d. do all of the above

D

Which of these includes both organisms and the physical environment?
a. population
b. community
c. ecosystem
d. species

C

K-strategists are likely to have higher dispersal rates than r-strategists.
A. True
B. False

B

The bubonic plague, which swept through Europe in the 14th century, is an example of ______ on human population growth.
a. density-dependent control
b. density-independent control

A

A(n) ______ always has a narrow niche.
a. generalist species
b. specialist species
c. alien species
d. keystone species

B

Natural selection involves all of these EXCEPT:
a) there is variation in traits within a population.
b) those individuals with more beneficial traits have a greater chance of surviving than other individuals.
c) individuals with a greater chance of surviving have a greater chance of having offspring than others.
d) all individuals in a population have the same likelihood of dying over a given period of time.

D

Which of the following is required for speciation to occur?
a. a change in climate
b. predation on weaker individuals
c. separation of one part of the population from another
d. rapid population growth
e. the initial species must be K-adapted

C

Factors capable of driving natural selection include:
a. competition with other members of the species.
b. disease-causing organisms.
c. extreme temperatures.
d. all of the above.

D

An organism's ________ includes its ________ .
A. ecological niche, habitat
B. habitat, ecological niche

A

The shape of a population's growth curve over time represents the dynamic interaction between a species' biotic potential and environmental resistance.
a. True
b. False

A

A dieback, or population crash, often occurs after a species ________ its environmental carrying capacity.
A. meets
B. overshoots
C. undershoots
D. oscillates around
E. decreases

B

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